The fall and early winter were active with several rains and mountain snow in the west. While this has helped alleviate any drought conditions and increased snowpack, the ground is increasingly saturated. AccuWeather meteorologists warn that continued rainfall will increase the risk of flooding and mudslides.

With Christmas this week, more people will be traveling by plane, train and car. The repeated rain and snowfalls are likely to cause people to drive more slowly and also delay airport traffic. In cities like Seattle and Portland, travel conditions could worsen as early as Monday.

“Travellers heading into the holiday season will experience wet roads along much of the West Coast, from the Canadian border to California,” said AccuWeather Senior Meteorologist Heather Zehr.

By Monday night and into Tuesday and Tuesday night, a new storm will move ashore and bring precipitation that could eventually fall as far south as Los Angeles.

“From Monday night into Tuesday morning, northern California and southwest Oregon will experience the heaviest rain, and decreasing snow totals will cause rain to transition to snow up to many passes,” Zehr explained.

“Although the amounts will not be excessive, once the snow begins the roads will quickly become slippery and heavy at times,” Zehr warned.

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During the duration of storms in the West, the amount of snow often rises and falls. This can lead to other hazards besides snowy and slippery roads.

“The shift in snow depth over the highlands will increase the risk of avalanches with each storm over the next week as increasing snowpack becomes more unstable,” warned Alex Sosnowski, senior meteorologist at AccuWeather.

For anyone traveling west on Christmas Day, most of the region will enjoy a brief respite from the rain and snow. The exception is a few snow showers in the Intermountain West. The next storm will hit the Pacific Northwest late today and overnight.

“Seattle will have periods of rain in the afternoon, while Portland may see a few showers in the late afternoon,” Zehr said.

The next storm is also expected to bring a lot of wind, especially as it initially moves inland on Wednesday evening and Thursday morning. If the ground is saturated and there is wind, there is a risk of at least local power outages. The greatest risk would be along the immediate coast, where the strongest winds are expected.

With severe weather expected this week and possibly even into the weekend, the rain amounts will add up.

“Rainfall totals during this series of storms through the end of the week will be 6 to 10 inches along the coast from Vancouver Island through Washington and most of Oregon and northern California,” Zehr said. “This will result in slight increases in flows with increasing risk following each storm.

“As the parade of storms continues, any additional storms will increase the flow and water levels of short-term rivers flowing from the Cascades, Coast Ranges and Olympics,” Sosnowski said. “Some rivers may flood unprotected areas along their banks.”

Although snow depths rise and fall, the highest peaks are likely to see snow throughout the duration of the storms.

“Above the pass in the mountains, particularly in the Washington Cascades and Sierra Nevada, a total of 2 to 4 feet of snow is likely,” Zehr said.

Looking further down the street, there could be a disruption in the Storm Parade heading into New Year’s Eve and New Year’s Day.

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